This proposal is in response to Program Announcement PA-09-070, AHRQ Health Services Research Projects Prevention/Care Management Portfolio requesting studies designed to improve the quality, safety, efficiency, and effectiveness of evidence-based preventive services and chronic care management, and improving the implementation of evidence-based recommendations on preventive services. Depression and cardiovascular disease are highly comorbid, and depression is a risk factor for psychosocial morbidity, poor adherence to medical treatment regimens, physical inactivity, poor physical functioning, and medical morbidity and mortality in cardiac patients, especially following an acute coronary syndrome (ACS). In 2006, an Evidence Report from the Agency for Healthcare Research and Quality (AHRQ) concluded that, despite strong evidence that depression is a risk factor for cardiac events, there was insufficient evidence to support the utility of depression screening in cardiac patients. There have been no studies since that time to determine the effectiveness of depression screening in cardiac patients. Nevertheless, the American Heart Association and other organizations have called for depression screening for ACS patients to improve identification and treatment of this risk factor. We propose to conduct a randomized, controlled trial comparing the effects of depression screening and case management to usual care in cardiology outpatients with a recent history of ACS. Patients being seen for an outpatient cardiology appointment at the Washington University Center for Advanced Medicine following hospitalization for ACS will be recruited for this study. Medically eligible patients will be administered the Patient Health Questionnaire-9 (PHQ-9) and the Beck Depression Inventory (BDI-II) to screen for depression. The first 300 patients who score 10 or above on the PHQ-9 will be randomly assigned to one of two conditions: Usual care, as provided by their cardiologist and primary care physician, or a collaborative depression screening intervention (CDSI). One hundred patients who score 9 or below on the PHQ-9 will also be recruited to determine the sensitivity and specificity of the PHQ-9 and BDI-II in relation to interview-based diagnosis of major depression. Patients will be followed for six months by a nurse case manager (NCM) who will periodically assess the patient's depression and treatment needs in consultation with a psychiatrist. Treatment recommendations will be made to the patient's primary care physician and monitored by the NCM. Referral to mental health professionals will be made as needed. Patients will be assessed at baseline, 3 and 6 months for current depression, depression treatment history, quality of life, physical functioning, adherence to medical treatment regimens, and the occurrence of adverse medical events in the 12 months following enrollment. Cost effectiveness analysis of the intervention will be conducted.